History of Flight
On 02 December 2015, at 04:45Z, a Sling 2 aircraft (registration ZU-WMM) departed from Wonderboom Aerodrome (FAWB) for a private flight with a pilot and one passenger. The pilot reported approximately three hours of fuel endurance. After about 0.3 hours of flight at 5800 feet above ground level, the engine's red warning light illuminated, and the engine failed within seconds. The pilot attempted to restart the engine but was unsuccessful. A forced landing was executed near the N1 freeway private airstrip. The aircraft struck a fence with its left wing before impacting the ground, then skidded approximately 70 metres on its belly before stopping.
Injuries to Persons
Both occupants sustained no injuries.
Damage to Aircraft
The aircraft sustained damage to the main landing gear, left wing tip, propeller blades, and the nose wheel collapsed.
Personnel Information
The pilot, a 21-year-old male, held a valid private pilot licence with a type endorsement for the Sling 2. His total flying experience was 135.9 hours, with 8.1 hours on type.
Aircraft Information
- Manufacturer: The Airplane Factory (Pty) Ltd
- Model: Sling 2
- Serial Number: 144
- Year of Manufacture: 2014
- Total Airframe Hours: 626.3
- Engine: Rotax 912, serial number 7703088, 626.3 hours since new
- Propeller: Airmaster AP332F, serial number 883, 626.3 hours since new
- Last Annual Inspection: 13 November 2015, at 600 airframe hours
Meteorological Information
Weather conditions were fine: temperature 26°C, visibility greater than 10 km, cloud cover 3/8 with no cloud base specified. Wind information from the South African Weather Services indicated wind direction 300° true at 2 knots, visibility 9999, temperature 31°C, and no cloud cover.
Wreckage and Impact Information
The aircraft impacted a boundary fence with its left wing before ground contact. It skidded on its belly for approximately 70 metres before coming to a halt. The propeller blades showed no signs of rotation at impact.
Tests and Research
An investigation by the Aircraft Maintenance Organisation concluded that the engine was operated at 6100 to 6500 revolutions per minute (RPM) for 11 minutes and 29 seconds. The maximum permissible RPM for the Rotax 912 is 5800 RPM for a maximum of 5 minutes, after which 5500 RPM should not be exceeded. The pilot was reportedly unaware of the over-rev warning on the EFIS screen. The engine failure resulted from high temperature caused by the sustained high RPM operation.
Conclusion
The probable cause of the accident was an unsuccessful forced landing following engine failure due to the engine being operated at high temperature, specifically at 6100 to 6500 RPM for 11 minutes and 29 seconds.